??? WLAN ???

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??? WLAN ???

• WLAN card ???

2
Reference

• Wireless Local Area Network by Dr.Morris Chang

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??

• ????
• ???????
• ????
• ????
• ????
• ????

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????

• ?????????????????
• ?? WLAN card ????
• ?? WLAN ?????

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???????

• 3-4??????,??????????????????
• ??notebook 3??
• ??????Netstumbler?Wireshark?Netterm?WSftp?

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Architectures
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Hidden Node Problem
A can communicate only with B. B can communicate
with A and C. C can communicate only with B. The
frame from A to B can be corrupted by
transmission from C
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4-Way Handshake

• RTS Request To Send
• CTS Clear To Send

A
B
RTS
CTS
Data
ACK
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No RTS/CTS

• If no hidden node problem
• RTS/CTS can be disable

A
B
Data
ACK
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Security

• WEP (Wired Equipment Protocol)
• WPA (Wi-Fi Protected Access)
• WEPTKIP802.1x
• WPA2
• WPAAES802.11i
• IEEE 802.1x ?????? 802.11 ??????? Ethernet
  ?????????802.1x ???????????????,???????????? (?
  RADIUS)?

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???? (1/3)

• ????????????
• ?? NetStumbler
• http//www.netstumbler.com/downloads/
• ??WS-FTP?Netterm???FTP server??,??????????
• ??PC????????configuration?
• Interface name?IP address?network mask?MAC
  address?default gateway...

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All APs
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Filter-WEP OFF
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Signal of AP
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???? (2/3)

• ?????????????
• ???? ? ?????? ? ?? ? ?? ? ?? ? ??
• ??3?notebooks(????A?B?C),??ad hoc mode,????????

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???? (3/3)

• ??????????????
• ??????????????
• ??WLAN???frame???????
• ??????RTS/CTS????
• ?????A??B??C????
• ???A?????????Internet,??????????B?C?ad
  hoc????A??Internet ?

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????

• ????????????????
• ?????????,?????
• ??100??
• ????????????